woodchurch science

we don’t see many of these in secondary schools these days but it’s worth being aware that they haven’t gone away…




head lice are blood sucking ectoparasites of humans from the family pediculidae, and they have world-wide distribution. this common human parasite is strictly host specific and does not affect other animals. an adult head louse is a small six legged insect, 2.5-3.5mm in length, with well developed eyes, small antennae and a flattened light brown body which is slightly lobed at the margins. the claws on each leg enable the lice to hold on to hairs, and they can run quickly over the scalp through hair.
head lice live their entire life (about a month) on the head of their host, and are often concentrated towards the back of the head and above or behind the ears. all nymphs and adults blood feed on the surface of the scalp until fully engorged, and can feed at any time of the day or night. a female head louse can lay 6-8 pale coloured oval shaped eggs (or nits) a day, and may lay 300 eggs within her life-span. the eggs are glued to the base of the hair shaft and grow out with the hair. the further away from the scalp that eggs are found can be an indicator of the length of the infestation (and most eggs found further than 1cm from the scalp should be hatched or are dead). Most eggs hatch within 7-10 days but some can remain un-hatched for up to 3-4 weeks.
without a blood-meal and the humid environment their human host provides, head lice will only survive a few days. they cannot infest furniture, bedding, pets or other household situations - they must have a human host.
transfer of head lice to individuals is by hair to hair, head to head and close bodily contact. sharing combs and brushes etc is the other main way that lice can spread. lice will not voluntarily leave the scalp. head lice tend to be more common among children than adults, and do not discriminate between sex or hair colour. head lice do not prefer dirty or unkempt hair, but may go unnoticed and proliferate in such an individual compared with one who pays attention to their hair. however, an infestation should not be seen as a reflection on personal hygiene, home environment or social status, and should not be seen as a social stigma.

divers have discovered a new crustacean in the south pacific which resembles a lobster and is covered with what looks like silky, blonde fur, french researchers say. scientists said the animal, which they named kiwa hirsuta, was so distinct from other species that they created a new family and genus for it. a team of american-led divers found the animal in waters 2300 metres deep at a site 1500 kilometres south of easter island. the animal is white and 15 centimetres long - about the size of a salad plate and its pincers are covered with sinuous, hair-like strands. it’s also blind. researchers found it had only “the vestige of a membrane” in the place of eyes. more information here

yves brun and colleagues from indiana university discovered that the world’s strongest glue is produced by the bacterium caulobacter crescentus to stick to river rocks. the adhesive can withstand an enormous amount of stress, equal to the force felt by a 10 pence piece with more than three cars piled on top of it. That’s two to three times more force than the best retail glues can handle. “there are obvious applications since this adhesive works on wet surfaces, one possibility would be as a biodegradable surgical adhesive.” but making it has proved challenging. like a mess of chewing gum, the gunk globs to everything, including the tools used to create it. “we tried washing the glue off,” brun said. “but it didn’t work!”

caulobacter crescentus grabs solid objects with its stalk and holdfast. in the picture, two ’stalk’ cells (at the bottom) spawn mobile clones of themselves.

the outermost ring of Uranus, discovered just last year, is bright blue, making it only the second known blue ring in the solar system, according to a report this week in the journal science. both blue rings are associated with smaller orbiting moons. you can read more about these findings here or here or even here.

ever gone to bed with a fresh glass of water and woken up to find bubbles on the side of the glass? this is due to solubility. air is more soluble in cold water (from your tap) than in warmer water (just sitting there for 8 hours). so any dissolved air, comes out of solution and forms tiny bubbles. remember that this is different to the behaviour of solids in liquids where they are generally more soluble in hotter solvents.

jayde hughes 7xw correctly identified the picture as that of a cats tongue, well done jayde:

click here for the full version.
clue one: this is part of many household pets
clue two: the only muscle in the body that’s attached at only one end

lewis judge (7ye) has posted a question asking how chameleons change colour. the chameleon has several cell layers beneath its transparent skin. these layers are the source of the chameleon’s colour change and some of the layers contain pigments, while others just reflect light to create new colours.

several factors contribute to the colour change. a popular misconception is that chameleons change colour to match their environment. this isn’t true. light, temperature, and emotional state commonly bring about a chameleon’s change in colour. the chameleon will most often change between green, brown and grey, which coincidently, often matches the background colours of their habitat.

hope this answers your question lewis! thanks for asking.

need new wallpaper for your pc. then this site recommended by mr wilkinson gives you a science ‘picture of the day’ to choose from. hundreds of pictures in their archives and each picture gives you even more links to follow.

mr sanders made some crystal gardens with one of his teaching groups. some ‘water glass’ (sodium metasilicate) is put into a jar then some sand is added followed by a few crystals of various substances. the garden then begins to grow. here are some example photographs.

this competition is now closed. The winner was jayde hughes who correctly identified the picture as that of a leech. see mr warren to collect your prize.

leeches are hermaphroditic aquatic animals that are now used commonly in medicinal applications. they secrete a chemical which prevents clotting of the blood.